1. Field of Invention
The invention relates to a color wheel and more particularly to a color wheel, which is used for preventing oil leaking.
2. Related Art
Currently, image projection systems have become popular items in the optoelectronic industry owing to multiple requirements of a system having large display area, small dimension, and thin, light composition. Thus, with the modern technology, only plasma display and projection system can fit the needs. However, due to the high price of the plasma display, the projection system becomes the priority choice in the market.
The popular projection systems are divided into three types including a liquid crystal display (LCD) type, a liquid crystal on silicon (LCOS) type, and a digital light processing (DLP) type, wherein the LCoS and DLP types have a simplified system and use a color wheel for providing color separation mechanism. The following description will take the DLP type projection system as an example.
In a DLP projector, a digital control method and a light reflection principle are adopted. First, light rays are integrated or converged by a light integration rod and then pass through the color filter of the color wheel, which splits the light rays. The split light rays are then projected onto a digital micro-mirror device (DMD). In this technology, the DMD is used to replace the liquid crystal panel for representing images in the conventional liquid crystal projector. Since the DMD includes several movable micro-mirrors, driving electrodes may control the tilt angle and deflection time of each movable mirror. Then, the light rays may be projected to form an image by switching the reflection directions of the light rays.
As shown in FIG. 1, in a projection system 1, a color wheel 11 has to rotate at high speed, so a motor 112 rotating the color filter 111 has a high operation temperature. However, since the housing 1121 of the motor 112 is riveting to the axis 1122, the oil in the motor 112 would leak or diffuse through the riveting point and then condense on the color filter 111. In more details, the oil is provided to lubricate the bearing of the motor. When the temperature is raised caused by the operation of the color wheel, the oil may be evaporated. The evaporated oil may diffuse through the leak of the riveting point and then attach to the color filter 111. Since the temperature of the color filter 111 is lower than the inside of the motor 112, the evaporated oil condenses on the color filter 111 so as to form white mist oil thereon. The white mist oil attaching on the color filter 111 would affect the light path and influence the image quality of the project system 1. In addition, the color wheel 11 may include glue or adhesive, which is made of polymers. The glue or adhesive may also generate some outgased chemicals due to the high operation temperature, and affect the light path and influence the image quality according to the above-mentioned mechanism.
It is therefore a subjective of the invention to provide a color wheel to solve the above-mentioned problems.